Plastically deformable inter-osseous device

ABSTRACT

Described here are deformable monolithic, stabilization devices, or implants, suitable for use within bone and between bones, for instance, to fuse vertebral bodies, to repair herniated discs, or to repair spinal compression fractures. The implants are introduced into a chosen site at a first, smaller height and then plastically deformed to achieve a second, but unique, pre-selected, larger height. Variations of the device provide one or more specific larger heights. The devices are particularly suitable as intervertebral spinal fusion implants for the immobilization of adjacent vertebral bodies. Methods of deploying the implants are also described as are instruments for such deployment.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.14/580,391, filed on Dec. 23, 2014, now U.S. Pat. No. 9,101,488, whichis a continuation of U.S. application Ser. No. 14/140,017, filed on Dec.24, 2013, now U.S. Pat. No. 8,920,507, which is a continuation of U.S.application Ser. No. 13/809,329, filed Jan. 9, 2013, now U.S. Pat. No.8,641,769, which is a National Stage Application under §371 of PCTApplication No. PCT/US2011/042056, filed Jun. 27, 2011, which claimspriority to U.S. Provisional Patent Application No. 61/364,521, filedJul. 15, 2010, the entire contents of which are incorporated byreference herein.

FIELD

Described here are deformable, monolithic, stabilization devices, orimplants, suitable for use within bone and between bones, for instance,to fuse vertebral bodies, to repair herniated discs, or to repair spinalcompression fractures. The implants are introduced into a chosen site ata first, smaller height and then plastically deformed to achieve asecond, but unique, pre-selected, larger height. Variations of thedevice provide one or more specific larger heights. The devices areparticularly suitable as intervertebral spinal fusion implants for theimmobilization of adjacent vertebral bodies. Methods of deploying theimplants are also described as are instruments for such deployment.

Also described are variations of the device particularly suitable assizing instruments. These versions are elastic, i.e., not plasticallydeformable, and may be restored to their original size. Many of thedescribed variations include deformable regions serving as hinges. Othervariations are non-monolithic or may have one or more classical hingessubstituted for the deformable regions.

BACKGROUND

Some conditions of the spine result from degradation or injury to thebone structures, e.g., the vertebral bodies, of the spine. Theseconditions may be the result of bone degeneration such as byosteoporosis or trauma, or by injuries such as compression fractures.Any of these maladies can cause great pain.

Other ailments of the spine result in degeneration of the spinal disc inthe intervertebral space between the vertebral bodies. These includedegenerative disc disease and traumatic injuries. In any case, discdegeneration can cause pain and other complications. That deformation iscommonly known as a herniated or “slipped” disc. The protrusion maypress upon one or more of the spinal nerves exiting the vertebral canalthrough the partially obstructed foramen, causing pain or paralysis inthe area of the spinal nerve's influence. Conservative treatment caninclude non-operative treatment requiring patients to adjust theirlifestyles and submit to pain relievers and a level of underlying pain.Operative treatment options include disc removal. This can relieve painin the short term, but also often increases the risk of long-termproblems and can result in motor and sensory deficiencies resulting fromthe surgery. Disc removal and more generally disc degeneration diseaseare likely to lead to a need for surgical treatment in subsequent years.The fusion or fixation will minimize or substantially eliminate relativemotion between the fixed or fused vertebrae. In surgical treatments,adjacent vertebra may be fixated or fused to each other using devices orbone grafts. These may include, for example, screw and rod systems,interbody spacers, threaded fusion cages and the like.

Some fixation or fusion devices are attached to the vertebra from theposterior side. Such devices protrude from the back and require hardwarefor separate attachment to each vertebra. Fusion cages and allograftsare contained within the intervertebral space, but must be inserted intothe intervertebral space in the same dimensions as desired to occupy theintervertebral space. This requires that an opening sufficient to allowthe cage or graft must be created through surrounding tissue to permitthe cage or graft to be inserted into the intervertebral space.

The described implants are suitable for fusing adjacent vertebrae whereat least a portion of the natural disc between those vertebrae has beenremoved but are introduced into the volume at a small profile that isexpanded to a larger profile after placement.

Human vertebral bodies have a hard outer shell of compacted, densecortical bone (sometimes referred to as the “cortex”) and a relativelysofter, inner mass of cancellous bone. Just below the cortex adjacentthe disc is a region of bone referred to as the “subchondral zone.” Theouter shell of compact bone (the bony endplate) adjacent to the spinaldisc and the underlying subchondral zone are often referred to as thebony “end plate region.” The endplate region is the densest boneavailable to support a fusion implant. Removal of, or compromise of, theendplate region by preparing the bone surface, e.g., by cutting into orboring into the cortex, allows implants to contact the softer and lessdense cancellous bone that lies beneath the endplate. It is desirable tomaintain the integrity of the cortex, if possible, in implanting fusiondevices.

Complicating this desire to maintain the integrity of the vertebral bonesurface adjacent the disc is the fact that that surface is somewhatdome-shaped. Such a dome-shaped surface does not always provide apredictable surface upon which to situate a fusion device. Additionally,many maladies related to discs cause the situations requiringdistraction of the discs as part of the treatment. This means that thespace between vertebrae is small.

There are a variety of implants for spinal fusion in current use.

One such implant has a modified cylindrical or tapered cylindricalshape. Implantation of such an implant requires a drilling step tocreate an adequate opening into the intervertebral space and a boreacross the faces of the endplates. Since the surfaces of the upper andlower vertebral bodies adjacent the disc space are dome-shaped, someadditional consideration must be given to gaining adequate contactbetween the vertebral bodies and the implant to achieve fusion.

One solution is shown in U.S. Publ. Appl. No. 2006/0241774, to Attali etal, in which a cylindrical plug is inserted into a bore in theintervertebral space and then expanded.

Non-cylindrical implants that are pushed into the disc space after adiscectonmy are also known. Although these push-in implants do have theadvantage of supporting the adjacent vertebral bodies by contacting asubstantial portion of the vertebral endplates, they do not offer theadvantages associated with threaded cylindrical implants that arescrewed into a bore in the adjacent vertebral bodies to more securelyhold these implants in their final fully seated positions. Further,unless the endplate is at least partially decorticated, i.e. worked uponto access the vascularity deep to the outer most aspect of the endplateitself, fusion will not occur.

The implants are suitable as actors in vertebroplasty. Vertebroplasty isan image-guided, minimally invasive, nonsurgical, distractive, therapyused to strengthen broken vertebrae, whether the vertebrae are weakenedby disease, such as osteoporosis or cancer, or fractured by stress.

Spinal fusion and vertebroplasty procedures often include a step ofinjecting an orthopedic cement mixture into the intervertebral space orinto the fractured bone. The cement mixture may contain particulateosteogenic materials, e.g., mixtures of one or several calcium phosphatepowders that react with water to form other calcium phosphate compounds,often an apatite, or others listed below. These cement mixtures arequite viscous and are difficult to inject through small diameteropenings. Providing large passageways through the implant allows passageof the cement through the implant.

None of the cited documents disclose the described deformable implant.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-1C show perspective views of one variation of the implant,respectively, in collapsed form, partially expanded form, and fullyexpanded form.

FIGS. 2A and 2B are schematic drawings showing operation of somevariations of the implant.

FIGS. 3A and 3B show perspective views of one variation of the implant,respectively, in collapsed form and fully expanded form.

FIGS. 4A, 4B, and 4C show, respectively, side, top, and end views of thevariation of the implant shown in FIGS. 3A and 3B.

FIG. 5 is a graph and table showing potential expandability of aspecific variation of the implant shown in FIGS. 3A and 3B.

FIGS. 6A and 6B show side views of one variation of the implant,respectively, in collapsed form and fully expanded form.

FIGS. 7 and 8 show side views of multi-cell versions of the describedimplant.

FIG. 9 shows a side view of a version of the implant having multipleexpansion points.

FIGS. 10A, 10B, and 10C show side views of a multi-level variation ofthe implant, respectively, in collapsed form, partially expanded, andfully expanded form.

FIGS. 11A and 11B show perspective views of one variation of animplantation tool with, respectively, a collapsed implant and anexpanded implant.

FIGS. 12A and 12B show perspective, close-up views of the distal sectionof the implantation tool shown in FIGS. 11A and 11B with, respectively,a collapsed implant and an expanded implant.

FIGS. 13A and 13B show perspective, close-up views of the distal sectionof the implantation tool shown in FIGS. 11A and 11B.

FIGS. 14-17 show examples of implantation procedures for the implant.

DESCRIPTION

Described herein is a bone stabilization device that may be used in aninterosseous space, i.e., inside a bone or between bones, where thespace is defined generally as being directly or indirectly between bonysurfaces. In particular, the described device is suitable as anintervertebral spinal fusion implant that is introduced at a low profileand expanded to a high profile at the implantation site. The implant maybe monolithic and expanded by deformation of the monolithic body. Inmany variations, the implant may be expanded to a unique preselectedheight. Other variations of the implant may be expanded to a specific,discrete height selected from two or more unique preselected heights.Expansion of the implant from the low profile rotates components of oneor more, partial, load-bearing, integral, support columns into alignmentupon reaching the final high profile. The expansion takes place in asingle plane or single direction. The components of the support columnsmay latch to each other or otherwise interact or engage with each otherto limit the expansion to the specific, discrete, predetermined heightsor to lock the implant into the expanded configuration while providinghigh compressive strength to the implant.

Described here are monolithic implants that are expanded from a lowerheight to a higher one by permanent, plastic deformation of the implantin a particular plane. The implant incorporates partial supportcomponents that become aligned during the process of deformation (andexpansion) and cooperate to form a complete support component thattypically supports a major portion of stress applied to the implant. Insome variations of the implant, there may be a small gap between thepartial support components after expansion; the small gap may disappearupon compression during use.

FIGS. 1A-1C show a variation of the implant showing the generalizedexpansion by deformation and providing a set of common terms forcomponents of the implant and its geometry.

FIG. 1A shows the implant (100) in its lower profile configuration asmight be utilized during initial introduction of the implant into atreatment site. FIG. 1B shows the implant (100) during the course ofexpansion. FIG. 1C shows the implant (100) after complete expansion andpermanent deformation of the device.

Returning to FIG. 1A, the implant (100) includes an upper bone contactsurface (102) and a lower bone contact surface (104) that, when theimplant (100) is expanded, generally contact adjacent bone surfaces,e.g., vertebral bone surfaces facing or defining a volume betweenvertebrae in a spine from which a natural disc has been removed inpreparation for the implantation of the device. As will be discussedbelow, the implant has a variety of uses other than as a spinalstabilizer or fusion block.

Often, bone contact surfaces (102, 104) will include fixation componentsof some design, e.g., spikes, serrations, fins, etc., as will bedescribed below. These fixation components have the goal of limitingmovement of the implant along (or parallel to) the bone surface and, insome instances, provide for permanent ingrowth between bone and implant.

The upper and lower bone contact surfaces (102, 104) each have a width(101), generally perpendicular to the longitudinal axis (103) of theimplant (100) and a length (105) along and generally parallel to theaxis (103) of the implant (100). The collapsed height (107) of thisvariation of the implant (100) is the distance between the upper andlower bone contact surfaces (102, 104) prior to expansion.

The upper and lower bone contact surfaces (102, 104) may includeopenings (106, 108) allowing osteogenic materials to flow into thecenter volume of the implant and to pass through that volume to adjacentbone surfaces thereby aiding in fusion of the implant to and betweenadjacent bony surfaces.

In any event, the device comprises a plurality of rotating or locatorarms (110) that rotate around deformation joint areas (112). Thislocator arm (110) design includes lands (114) at each end of the locatorarms (110) that contact surfaces on the bone contact surface structure(116). Rotation of the locator arms (110) and the resultant deformationof the deformation joint areas (112), causes expansion of the implant(100) to the expanded height (109) shown in FIG. 1C.

Central to this variation of the device are the deformation joint areas(112). Those joints (112) are regions or areas of the device locatedbetween substantially inflexible regions or structures of the device.The joints have two functions: 1.) each provides a center of rotation orlocus of bending between the adjacent inflexible regions—a hingingeffec—, and 2.) each provides a region in which, after expansion, all ofthe deformation in the device is located.

The deformation joints (112) shown in FIGS. 1A-1C may be operative toprovide a sharp bend, as may be seen in FIGS. 1A-1C, in which thedeformation is located in a comparatively smaller area or may beoperative to provide a longer bend in which the deformation is locatedin a comparatively larger area.

The deformation joints (112) may be formed by providing a reducedcross-sectional area of a structural component. The reducedcross-section provides a region of reduced strength and localizedbending and, in properly chosen materials, plastic deformation.

In the variation shown in FIGS. 1A-1C, the deformation joint areas (112)permit bending and deformation between the substantially inflexiblelocator arms (110) and the substantially inflexible upper or lower bonecontact surface structures (116). Although I use the term “substantiallyinflexible” with respect to the locator arms and columns, thosecomponent structures will have some amount of flexibility due to thesize and materials of manufacture of the components. In general, thelocator arms and columns are less flexible, typically significantly lessflexible, than the deformation joint areas.

FIG. 1B shows the implant (100) after it has been partially deformed atan angle (a). The implant is expanded by providing differential,relative movement between upper bone contact surface (102) and the lowerbone contact surface (104). That differential movement expands thedevice in only a single direction, the height.

As the device (100) is deformed and expanded through the sequence shownin FIGS. 1A-1C, cooperating partial load-bearing columns, an upperpartial column (120) and a lower partial column (122), move intoalignment and engage to form a complete column as the expansion iscomplete. The term “engage” is meant herein to encompass situations inwhich the two partial load-bearing columns (120, 122) are in contact andin which the two partial load-bearing columns (120, 122) include a smallgap between them after expansion, provided that the gap disappears underload during use.

As shown in FIG. 1C, the partial load-bearing columns (120, 122 and 124,126), after expansion, provide the major load-bearing component forloads imposed upon the upper and lower bone contact surfaces (102, 104).A pair of partial load-bearing columns (124, 126) is situated on theopposite side of the device (100).

The variation of an implant shown in FIGS. 1A-1C includes upper andlower bone contact surfaces (102, 104) that are substantially parallel.As discussed below, these surfaces need not be parallel. For instance,when the implant is used to replace a lumbar disc, the implant may bedesigned in such a way that the bone contact surfaces are not parallelto provide a lordotic angle after implantation. This concept will bediscussed further below.

The upper and lower bone contact surfaces (102, 104) are shown to besubstantially flat, but may have shapes or forms, e.g., partiallycylindrical, rounded, elliptical, spherical, etc. Such shapes may bechosen, e.g., to perform or provide a specific function or to match ananatomical shape.

FIGS. 2A and 2B show, in schematic fashion, an explanation of one aspectof the operation of the implant, and explaining in particular, thegeometry of the generally inflexible members discussed above, both whenthe device is collapsed (as at implantation) and when it is expanded.

FIG. 2A shows a variation of the implant similar to those shown in FIGS.1A-1C and 3A-3B. In this variation, the device (200) has substantiallyparallel lower (202) and upper (204) bone contact surface structures.The locator arms (206) in this variation are also substantiallyparallel. Each of the upper and lower bone contact surfaces (202, 204)and the locator arms (206) are considered to be inflexible.

In step (a), the device (200) is depicted in a collapsed form. As thelower and upper bone contact surface structures (202, 204) are moved inthe directions shown by arrows (208, 210), the inflexible rotator arms(206) rotate about their deformation joints (212) to result in theexpanded condition shown in step (b).

FIG. 2B shows a device (220) in which neither pair of inflexiblemembers, i.e., upper and lower bone contact surface structures (222,224) or distal and proximal locator arms (226, 228), are parallel. Asnoted elsewhere, an expanded structure in which the bone contactsurfaces (227, 224) are not parallel, may be useful in treating certainconditions or portions of the anatomy where the adjacent bone surfaceseither are not generally parallel and should be or that are not paralleland should remain so.

Step (a) shows the device (220) in a collapsed form. As the upper andlower bone contact surface structures (222, 224) move in relativedirections generally opposite each other (230, 232). The variousinflexible members (222, 224, 226, 228) rotate about deformation joints(230) to result in the structure schematically depicted in step (b).

The final expanded shape of the implant (220) is fixed using componentsnot shown in FIGS. 2A and 2B—the partial column supports discussed aboveand shown in FIGS. 1A-1C.

FIGS. 3A and 3B show perspective views of another variation of thedevice (250), respectively in collapsed form and in expanded form. FIGS.4A, 4B, and 4C show side, top, and end views of that implant (250).These figures provide greater detail of certain ancillary features ofthe implant, e.g., components useful in expanding and implanting thedevice in cooperation with suitable instrumentation, bone anchoringfeatures, and latch components operative as portions of the supportcolumns.

The variation (250) depicted in FIGS. 3A, 3B, and 4A-4C includes bonecontact surfaces (252, 254) that are parallel both in the compressedform and in the expanded form. As noted above, the geometry of theinflexible components of the implant need not involve parallel surfaces,but may be non-parallel if desired.

FIG. 3A shows an upper bone contact surface (252) defined by theunderlying bone contact surface structure (256). A lower bone contactsurface (254), not seen, is defined by the lower bone contact surfacestructure. The upper bone contact surface (252) includes a number ofserrations (259) serving a bone anchoring function. These functionalanchors may assist in holding a bone contact surface on the implant(250) in position during implantation or may hold the implant inposition after implantation. Other forms of functional bone anchoringcomponents, e.g., fins, spikes, hooks, etc., may be substituted as thedesigner desires.

Deformable joint regions—encompassing acute angles (260) and obtuseangles (262)—are seen at each corner of the device (250). These jointregions are physically defined by their actual deformation duringexpansion of the device (250) and ultimately after the device (250) isfully expanded. The inflexible regions between deformable joint regions(260, 262) are either bone-contact surface structures (256, 258) orlocator arms (264).

This variation of the implant (250) includes upper and lower partialload-bearing columns (266, 268) that move into contact (as shown in FIG.3B) as the implant is expanded and ultimately latch together byintermeshing a pair of teeth (270) at the apex of the upper andlowerpartial load-bearing columns (266, 268). After latching, the twopartial load-bearing columns (266, 268) form a complete load-bearingcolumn.

FIG. 4A shows a side view of the implant (250). The deformable jointregions (260, 262) include thinned areas accentuating the devices'tendency to deform only in those regions. As a practical matter, wherethe implant is monolithic, thinning a region of the implant to formdeformation regions for the “hinging” effect is an excellent way toproduce such regions. Other ways, e.g., localized annealing of thedesired deformation regions, localized hardening of thenon-deformation-regions, and providing a different, elasticallycomposition in the deformation regions are also suitable but providedwith less ease.

FIG. 4A shows another optional feature: the faces (269) or edges of thepartial load-bearing columns (268) that are adjacent each other do notcontact each other until the latching teeth (270) form the load-bearingcolumn at expansion. Those surfaces (270) may, of course, be in contact.

FIG. 4B is a top view of the implant (250) showing the bone contactsurface and its serrations (259). In particular, the drawing shows thelarge openings (274) allowing access from the interior of the implant(250), e.g., osteogenic materials, bone cement, granular bone, etc., maybe introduced to the bone surfaces adjacent a properly positionedimplant (258) through the center of the implant (250). Suitableosteogenic materials are discussed below. The sizes of the openings maybe larger or smaller as desired or as dictated by the implant use.

FIG. 4C provides an end view of the implant (250). The acute-angledeformable joint region (260) may be seen. The figure also shows alongitudinal passageway (276) allowing passage of osteogenic fillermaterial.

FIG. 5 is a graph and table relating to the expandability of a number ofexamples of the implants of the design shown in FIGS. 3A, 3B, and 4A-4C.A small implant having a 6 mm collapsed height expands to 7.5 mm, a 25%increase in height. The larger implant having a 10 mm collapsed heightexpands to 14.5 mm, a 45% increase in height. Other sizes and expansionratios may be designed. Expanded lengths of between 5 mm and 30 mm andexpanded heights of about 2 mm and 15 mm are practical sizes and easilydesigned based upon the directions provided here. Similarly, expandedaspect ratio (length:height) between 0.5 and 4:1 are easily designedalthough I have found ratios in the range of 1.5:1.0 to 3:1.0 to bequite useful in implants for human spinal fusion service.

FIGS. 6A and 6B show perspective views of another variation of thedevice (271), respectively in collapsed form and in expanded form. Thisvariation (271) is substantially similar to the variation shown in FIGS.3A and 3B except that the implant comprises two sets of interlockingteeth (270).

Specifically, this variation of the implant (271) includes upper andlower partial load-bearing columns (266, 268) that move into contact (asshown in FIG. 6B) as the implant is expanded and ultimately latchtogether by intermeshing two pairs of teeth (270) at the apex of theupper and lower partial load-bearing columns (266, 268). After latching,the two partial load-bearing columns (266, 268) form a completeload-bearing column.

FIGS. 7 and 8 show implants that are, in essence, multi-cell variants ofthese shown in FIGS. 3A-4C.

FIG. 7 shows a multi-cell implant (280) having two stacked integralcells (282) in a single monolithic device. This variation is suitablefor a vertebral body replacement (“VBR”), i.e., a replacement for a pairof discs and a vertebra in a spine. The multiple, but short, partialcolumn supports (289) provide added stability to such a long device. Thedevice (280) is shown in a collapsed condition. In this variation,expansion of the device (280) involves differential or relative movementof center section (284) in the direction of the arrow (286) withrelation to the upper bone contact area (288) and the lower bone contactarea (290).

FIG. 8 shows a multi-cell implant (300) having two integral cells (302)placed end-to-end in a single monolithic device. The device (300) isshown in a collapsed condition.

FIG. 9 shows a variation of the implant (304) having multiple—in thisinstance, two—discrete, pre-determined expansion sizes. The overalldesign is similar to the design seen in FIG. 3A-4C. The device (304) hasan upper partial load-bearing column (306) and a lower partialload-bearing column (308). The lower partial load-bearing column (308)includes a pair of teeth (310) at its apex forming a portion of anexpansion latch. The upper partial load-bearing column (306) includestwo latching sites—a lower height site (312) at an intermediate positionon the upper partial load-bearing column (306) and a higher height site(314) at the apex of the upper partial load-bearing column (306). Afterlatching the pair of teeth (310) situated on the lower partialload-bearing column (308) with one or the other of the lower height site(312) or the higher height site (314), the two partial load-bearingcolumns (306, 308) form a complete load-bearing column at one of thepredetermined heights.

FIGS. 10A-10C show side views of still another variation of my device(320) in which multiple expanded sizes may be selected uponimplantation. FIGS. 10A, 10B, and 10C show respectively the collapseddevice, the device expanded to a first height, and the device expandedto a second height. Although the implant (320) is facially similar tothe device (304) shown in FIG. 9, the deformable regions (322) adjacentthe upper deformable joint regions (324) are not substantially stiff incomparison to the upper extended bone contact surface (307) of the FIG.9 device. If ultimate effect, this variation provides an expandedimplant having a smaller upper bone contact surface (326) than its lowerbone contact surface (328). These deformable regions (322) permitreformation of the overall structure to various heights in anapproximate trapezoidal shape.

This variation of my device (320) also has an upper partial load-bearingcolumn (330) and a lower partial load-bearing column (332). The upperpartial load-bearing column (330) includes two latching sites—a lowerheight site (340) at an intermediate position on the upper partialload-bearing column (330) and a higher height site (338) at the apex ofthe upper partial load-bearing column (330). The lower partialload-bearing column (332) includes a pair of teeth (334) at its apexforming a portion of an expansion latch. After latching the pair ofteeth (334) situated on the lower partial load-bearing column (332) withone or the other of the lower height site (340) or the higher heightsite (338), the two partial load-bearing columns (330, 332) form acomplete load-bearing column at one of the predetermined heights. Thedeformable regions (332) and the deformable joint regions (324) havebeen deformed to the shape seen in FIG. 10B or in FIG. 10C.

This device, such as shown in FIG. 9 or 10A-10C may be expanded tospecific, unique, predetermined heights by pre-selection of the geometryand placement of the latching sites (or other engagement sites) on thepartial load-bearing columns. By “specific” or “discrete” or “unique” or“predetermined,” when referring to height, is meant that the device mayonly be expanded to a height value that is a substantially single valueand is stable, i.e., the device is able to support the anatomical loadin that position. Instrumentation. The compression of the device usinganatomical pressures after expansion will result in less than about 5%of the total expanded height. As discussed with regard to the devicesshown in FIGS. 7 and 9, there may be multiple singular, discrete valuesof the expanded height. Finally, the number of unique, expanded heightvalues for a particular device is equal to the number of pre-configuredstability structures, e.g., latching sites or other engagement sites,included in the device.

Kits of any of the implants discussed above where the implants areselected to include a variety of expanded heights, or selected to havethe same expanded height and either differing collapsed heights ordiffering device widths, or selected to include differing angles betweenthe top and bottom bone contact areas, or selected to have a variety ofexpanded heights with equal differences between the collapsed andexpanded states. Each of these kits may further be included withinstrumentation to introduce the implants into a chosen site in thehuman body. Each of these kits may further include written instructionsfor use.

FIG. 11A shows a perspective view of one variation of instrumentation oran implantation tool (400) with a collapsed implant (402) and FIG. 11Bshows a perspective view of the implantable tool (400) with an expandedimplant (404). The implant (402, 404) in FIGS. 11A and 11B is thevariation shown in FIGS. 3A-4C.

As mentioned elsewhere, this variation of the implant (402) is expandedby providing relative motion between one bone contact face of theimplant (402) and the other face. The implantation tool (400)accomplishes such push-pull action. As will be discussed in more detailwith regard to FIGS. 13A and 13B, the tool (400) incorporates varioussurfaces that contact surfaces in the implant to pull a distal surfacein the implant and to push on a proximal surface (in a generally axialdirection) and to actively expand the implant (402).

The implant tool (400) is a straightforward design having a pull rod(406) with a fixture (408) for cooperatively mating with the implant(402) and having a stationary rod (410) that also includes a distalmating fixture (not seen in FIGS. 11A and 11B) that also removably mateswith a surface in the implant (402). The implant tool (400) incorporatesa twist knob (412) and a stationary grip body (414). A rotary motion(416) applied to the knob (412) applies a linear pulling motion (418) tothe pull rod (406). The proximal end of the pull rod (406) may, forinstance, be provided with screw threads (not shown) to cooperate withthreads associated with the twist knob (412) to provide such linearmotion. Included is a ratchet (420) to control the twisting direction ofthe knob (412) twist and potentially with a lock to maintain the tool(400)/implant configuration (402) in a fixed order prior to use.

This tool (400) provides the desired push-pull motion to expand theimplant (404) as shown in FIG. 11B.

FIG. 12A shows a close-up, perspective view of the distal tip (400 a) ofthe implantation tool (400) and gives a more detailed view of thepull-rod mating fixture (408) in contact with collapsed implant (402).The pull-rod (406) sits within a channel in the stationary rod (410).

FIG. 12B shows a close-up, perspective view of the distal tip (400 a) ofthe implantation tool (400) with the implant (404) after expansion. Inthis variation of the implantation tool (400), the pull-rod matingfixture (408) includes an expansion ramp (413). As the pull-rod (406) ispulled proximally, the expansion ramp (413) slides up on a cooperatingramp (415) associated with the stationary rod (410). Similar rampingcomponents are located more distally—moving ramp (416) on pull-rodmating fixture (408) and distal cooperating ramp (418) on stationary rodend (410).

FIGS. 13A and 13B provide close-up, perspective views of the distal endof the implantation tool (400 in FIGS. 11A and 11B) without an implantobscuring details of the tool. FIG. 13A shows the pull-rod (406), thepull-rod mating fixture (408), and the stationary rod (410). This viewshows the proximal expansion ramp (413) in contact with thestationary-rod cooperating ramp (415). This view also shows the distallylocated pull-rod moving ramp (416) in contact with the distalcooperating ramp (418) on the stationary rod (410).

The implant contacts two surfaces of importance on the pull-rod matingfixture (408) during implantation—the distal surface (432) locates andfixes the implant axially in place, the middle surface (434) supportsthe length of the implant as that side of the implant is pulledproximally during expansion. After expansion is complete, proximalsurface (430) disengages the implant and the pull-rod mating fixture(408) as the pull-rod (406) is returned to its starting position andallows removal of the implantation tool (400) from the expanded implant.

Similarly, a stationary surface (440) contacts the implant and maintainsit in position, in conjunction with long-wise surface (442) as theopposite side of the implant is pulled proximally and expanded using thepairs of cooperating ramps (413, 415) and (416, 418).

FIG. 13B shows the position of the pull-rod mating fixture (408) afterthe pull-rod (406) has been pulled proximally to expand the implant. Atthis final position, the implant is fully expanded and locked at thatexpanded size by the partial load-bearing columns (120, 122 in FIGS.1A-1C and 268 in FIGS. 3A-4A). As may be seen in FIG. 13B, the proximalexpansion ramp (413) is no longer in contact with stationary rodcooperating ramp (415). The pull-rod moving ramp (416) is no longer incontact with distal cooperating ramp (418). The middle surface (434) onthe pull-rod mating fixture (408) has moved away from surface (442)evidencing expansion of the implant.

When used as a fusion device for the spine, the device may be implantedusing any of a variety of approaches—anterior, posterior, lateral, etc.Because of the device's initial low profile, the device offersadvantages in lower risk transforaminal procedures, e.g., TLIFprocedures, or posterior procedures, e.g., PLIF procedures.

Moreover, the device may be expanded at the final placement site orexpanded nearby the final placement site and then moved there. Theimplant may be used to distract vertebrae, to properly align vertebrae,or simply to maintain intervertebral spacing. The devices may beexpanded in a direction along the axis of the spine or expandedlaterally in an intervertebral space.

Biocompatible Materials

The device may comprise a suitable metallic or polymeric material.

Suitable biocompatible metallic materials include pure titanium,tantalum, cobalt-chromium alloys, titanium alloys (e.g., nickel titaniumalloys and tungsten titanium alloys), and stainless steel alloys.Suitable polymeric materials include members of the polyaryletherketone(PAEK) family, e.g., polyetheretherketone (PEEK), carbon-reinforcedPEEK, polyetherketoneketone (PEKK); polysulfone; polyetherimide;polyimide; ultra-high molecular weight polyethylene (UHMWPE); orcross-linked UHMWPE. Ceramic materials such as aluminum oxide oralumina, zirconium oxide or zirconia, compact of particulate diamond, orpyrolytic carbon may be included in such polymers.

Osteogenic Compositions

All or a portion of the interior or periphery of the implant may befilled with a suitable osteogenic material or therapeutic compositiongenerally after implantation. Osteogenic materials include synthetic ornatural autograft, allograft, xenograft, demineralized bone, bone paste,bone chips, bone strips, structural bone grafts, hydroxyapatite, andcalcium phosphate; synthetic and natural bone graft substitutes, such asbioceramics and polymers; other tissue materials including hard tissues,connective tissues, demineralized bone matrix and combinations, andosteoinductive factors. Other bone growth promoting substances maycomprise platelet derived growth factors, bone marrow aspirate, stemcells, bone growth proteins, bone growth peptides, bone attachmentproteins, bone attachment peptides, hydroxyapatite, calcium phosphate,statins, and other suitable bone growth promoting substances.

Osteogenic compositions may include an effective amount of a bonemorphogenetic protein (BMP), TGF_(β1), insulin-like growth factor,platelet-derived growth factor, fibroblast growth factor, LIMmineralization protein (LMP), bone marrow aspirate, stem cells, bonegrowth proteins, bone growth peptides, and combinations thereof or othertherapeutic or infection resistant agents, separately or held within asuitable carrier material.

These materials may be mixed with resorbable materials such aspolylactide polymers, polyglycolide polymers, tyrosine-derivedpolycarbonate polymers, polyanhydride polymers, polyorthoester polymers,polyphosphazenes, calcium phosphate, hydroxyapatite, bioactive glass,PLLA, PLDA, and combinations.

Methods of Use

As noted elsewhere, the implants may be introduced to a treatment siteusing a number of different approaches—anterior, posterior, lateral,posterior-lateral, etc. Because of the low profile upon insertion, theimplant is especially useful in lateral and posterior approaches, e.g.,PLIF and TLIF approaches.

FIG. 14 shows the implantation of a variation of the implant into a sitehaving both a collapsed disc and spondylolisthesis (i.e., a conditionwhere a vertebra is displaced anteriorly in relation to the vertebrabelow). FIG. 14 is a lateral view of an upper vertebra (500) and a lowervertebra (502) separated by an implant (504) having a distal locator arm(506) that is longer than the proximal locator arm (508). Step (a) inthe FIG. 14 shows the site having both a collapsed disc andspondylolisthesis with the properly placed, but unexpanded, implant(504). In step (b), the implant (504) has been expanded. Expansion ofthe noted variation of the depicted implant (504) causes distraction ofthe vertebrae (500, 502), posterior displacement of the upper vertebra(502), and the restoration of a normal lordotic angle.

FIG. 15, step (a), shows a lateral view of an intervertebral sitebetween an upper vertebra (500) and a lower vertebra (502) that requiresonly height preservation.

Step (a) shows the collapsed implant (510) properly situated forimplantation. In step (b), the implant (510) has been expanded tocontact the surfaces of the vertebral bones. However, the vertebrae(500, 502) have not been distracted nor translated.

FIG. 16 provides a procedure for inserting an implant into anintervertebral space that requires distraction due to a collapsed disc,but without spondylolisthesis. In step (a), an implant (504) of the typediscussed with regard to FIG. 14—having a distal locator arm (506) thatis longer than the proximal locator arm (508)—is introduced into theintervertebral space and expanded sufficiently to allow contact with thevertebrae (500, 502). In step (b), the implant (504) is graduallyexpanded, distracting the vertebrae (500, 502), while being inserted(arrow at 512) into the intervertebral space. In step (c), the implant(504) is fully expanded and has been driven (arrow at 512) into theintervertebral space creating a lordotic angle between vertebrae (500,502). Using this gradual insertion and expansion procedure, the implant(504) is inserted into the intervertebral space only as far as isoptimum for the proper distraction of the vertebrae.

FIG. 17, step (a), shows a top view of a disc space into which animplant (520) has been laterally introduced. Unlike the other variationsdiscussed here, this implant (520) is used only as a spacer. In step(b), the implant has been expanded.

Other Variations

This device may be used other than as an implant. For instance, byconstructing the device from an elastic material, the device may be usedto measure the size of an interosseous volume. For instance, theinstrumentation shown in FIGS. 11A-11B (perhaps with indicia of thepush-pull distance traversed by the pull-rod (406 in FIGS. 13A and 13B)during expansion of the device.

Additionally, where particularly specified, one or more of thedeformation joints may be substituted with a classical multi-part hinge.One or more deformable regions may remain. Utilizing two or moreclassical hinges requires that the device not be monolithic.

It is to be understood that all spatial references, such as“horizontal,” “vertical,” “top,” “upper,” “lower,” “bottom,” “left,” and“right,” are for illustrative purposes only, typically to providerelative positions, and may be varied within the scope of thedisclosure.

Other modifications of the present disclosure would be apparent to oneskilled in the art. All such modifications and alternatives are intendedto be included within the scope of this disclosure as defined in thefollowing claims. Those skilled in the art should also realize that suchmodifications and equivalent constructions or methods do not depart fromthe spirit and scope of the present disclosure, and that they may makevarious changes, substitutions, and alterations herein without departingfrom the spirit and scope of the present disclosure.

What is claimed is:
 1. An orthopedic stabilizing device for placement inan interosseous space defined by adjacent bony surfaces, comprising adeformable monolithic body having a distal end, a proximal end and alongitudinal axis extending through the distal and proximal ends, saiddevice being expandable along a height axis between a first unexpandedheight to a second and third larger expanded height by deformation ofthe monolithic body, said body including longitudinally separated firstand second partial columns that are not engaged with each other at saidfirst height and operative to move longitudinally and engage uponexpansion to form a load-bearing column at one of said second largerheight or said third larger height.
 2. The device of claim 1, whereinsaid third height is greater than said second height, said second heightdefining an intermediate height of expansion and said third heightdefining a full height of expansion.
 3. The device of claim 2, whereinsaid monolithic body has a lower bone contact structure and an upperbone contact structure spaced from each other along the height axis,said first partial column being supported by said lower bone contactstructure and said second partial column being supported by said upperbone contact structure.
 4. The device of claim 3, wherein said firstpartial column has an apex directed toward said upper bone contactstructure.
 5. The device of claim 4, wherein said first partial columnincludes a first latch disposed at said apex of said first partialcolumn.
 6. The device of claim 5, wherein said first partial columnincludes a pair of teeth at said apex forming a portion of said firstlatch.
 7. The device of claim 5, wherein said second partial column hasa second latch and a third latch, said second latch being disposed onsaid second partial column closer to said upper bone contact structurethan said third latch, said second latch being engageable with saidfirst latch upon expansion of said device to form said load-bearingcolumn at said intermediate height.
 8. The device of claim 7, whereinsaid second partial column has an apex directed toward said lower bonecontact structure.
 9. The device of claim 8, wherein said third latch isdisposed at said apex of said second partial column, said third latchbeing engageable with said first latch upon expansion of said device toform said load-bearing column at said full height.
 10. The device ofclaim 1, wherein said deformable body is plastically deformable uponexpansion.